1. Field of the Invention
This invention relates to domestic furnaces, and in particular to a furnace having means for effectively separating and neutralizing acidic condensate from the flue gas and suitably discharging the condensate to a household drain.
2. Background Art
In U.S. Pat. No. 4,164,210 of George T. Hollowell, a domestic-type furnace is shown to have a secondary heat exchanger providing a high efficiency wherein the flue gases are discharged at a relatively low temperature whereby a portion thereof may condense. To remove any resulting condensate, a drain is provided at the bottom of the secondary heat exchanger.
A problem arises in a furnace system such as taught by the Hollowell patent in that the products of combustion of conventional hydrocarbon furnace fuels include acidic products. Natural gas, for example, frequently contains some amount of sulfur which, when burned with the gas, produces sulfur dioxide or sulfur trioxide in addition to the normal combustion products of carbon dioxide and water vapor. When condensed, these combustion products produce a weak sulfuric acid solution. The dumping of such acidic condensate directly into a conventional household drain may not be advisable in all cases. The present invention comprehends providing an improved neutralizing means for neutralizing such acidic condensate, permitting satisfactory discharge of the condensate into the conventional household drain.
A number of prior art patents disclose commercial means for the scrubbing of gas. Illustratively, Roger Kent, in U.S. Pat. No. 3,683,593, shows a gas scrubber having a wet filter bed with layers of stacked filter elements. The filter elements used may be spherical glass marbles, and the filter bed is periodically tilted or moved to displace the filter elements and enhance the gas scrubbing action. Charles S. Viers, in U.S. Pat. No. 3,735,567, shows a gas scrubber in the form of a muffler provided with a filter containing gas-cleaning water. The exhaust gas pressure is utilized to vaporize and circulate the gas-water mixture over the filtering material so as to improve the gas washing and filtering action and prevent clogging.
Henry Burbach, in U.S. Pat. No. 3,726,239, discloses a wet scrubber employing a bed of marble for producing a mixture of the wash water and flue gas. The Viers Patent 3,735,567 discussed above utilizes lime rock for neutralizing acid-forming components of the exhaust gases in the muffler structure.
In U.S. Pat. No. 3,751,231, Albert Niedzielski utilizes a porous acid ion exchange resin, such as a resin formed of sulfonated copolymer of styrene and divinylbenzene for removing amines from a steam distribution system.
Another furnace structure which discharges condensate from the flue gases directly to the building drain is shown in U.S. Pat. No. 3,944,136 of Edwin C. Huie.
John D. Hilliard, in U.S. Pat. No. 1,620,155, shown an attachment for oil insulated switches for preventing the throwing out of oil as upon opening of a high-power circuit under oil. Hilliard teaches the use of a housing enclosing a mass of gravel or artificially prepared spheroidal bodies in a serpentine flow path for separating much of the oil vapor and atomized oil from the discharging gases while, at the same time, cooling the gases to a low temperature for safe discharge to the external atmosphere.